Not Applicable
Not Applicable
Not Applicable
The following publications which are identified herein using a number inside parenthesis (e.g., (1)) are hereby incorporated by reference:
(1) American Diabetes Association. Diabetes 1996 Vital Statistics. Rockville, Md.: American Diabetes Association, 1996.
(2) Harris, M. I., Cowie, C. C., Stern, M. P. eds. Diabetes in America, 2nd. ed. National Institutes of Health. National Institute of Diabetes and Digestive and Kidney Diseases. NIH Publication No. 95-1468, 1995.
(3) Clark, C. M., Vinicor, F. Introduction: Risks and benefits of intensive management in non-insulin-dependent diabetes mellitus. The Fifth Regensrief Conference. Ann Intern Med, 124(1, pt 2), 81-85, 1996.
(4) Porte, J. and Schwartz, M. W., Diabetes complications: Why is glucose potentially toxic?, Science, 272, 699-700, 1996.
(5) Ishii, H., Jirousek, M. R., Koya, D., Takagi, C., Xia, P., Clermont, A., Bursell, S. E., Kern, T. S., Ballas, L. M., Heath, W. F., Stramm, L. E., Feener, E. P. and King, G. L., Amelioration of vascular dysfunctions in diabetic rats by an oral PKC xcex2inhibitor, Science, 272, 728-731, 1996.
(6) UKPDS Group. UK Prospective Diabetes Study 33: Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes. Lancet, 352, 837-853, 1998.
(7) Incidence and risk factors for serious hypoglycemia in older persons using insulin or sulfonylurea. Arch Int Med, 8, 25, 1997.
(8) Tight control for type 2 diabetes. Health News, 10, 25, 1998.
(9) Boyle, P. J., Kempers, S. F., O""Connor, A. M. and Nagy, R. J., Brain glucose uptake and unawareness of hypoglycemia in patients with insulin-dependent diabetes mellitus, New Eng J. Med 333(26), 1726-1731, 1995.
(10) Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med, 329, 977-986, 1993.
(11) American Diabetes Association. Implications of the Diabetes Control and Complications Trial. Diabetes Spec 6(4), 225-227, 1993.
(12) Lewin, D. I., Brain""s adaptation to low blood sugar endangers diabetics, J. NIH Research, 8, 38-39, 1996.
(13) Miller, J. L., Salman, K., Shulman, L. H. and Rose, L. I., Bed time insulin added to daytime sulfonylurea improves glycemic control in uncontrolled type II diabetes, Clin. Pharmacol. Ther., 53 (Mar), 380-384, 1993.
(14) Shank, M. L., Prato, S. D. and DeFronzo, R. A., Bedtime insulin/daytime glipizide, effective therapy for sulfonylurea failures in NIDDM, Diabetes, 44(2), 165-172, 1995.
(15) Labovitz, H. E., Glipizide : A second generation sulfonylurea hypoglycaemic agent, Pharmcotherapy, 5 (2), 63-77, 1985.
(16) Labovitz, H. E., Oral sulfonylurea hypoglycemic drugs, Pharmacy Times, 51, 108-116, 1985.
(17) Martindale, The Extra Pharmacopoeia, Thirtieth Edition, Eds. J. E. F. Reynolds, The Pharmaceutical Press, London, 1993.
(18) AHFS Drug Information, 1989, pp 1741-1745.
(19) Brogden, R. N., Heel, R. C., Pakes, G. E., Speight, T. M. and Avery, G. S., Glipizide : A review of its pharmacological properties and therapeutic use, Drugs, 18, 329-353, 1979.
(20) www.pfizer.com/hml/piand#39:s/glucotrolxlpi.pdf.
(21) Peterson, C. M., Sims, R. V., Jones, R. L. and Rieders, F., Bioavailability of glipizide and its effect on blood glucose and insulin levels in patients with non-insulin-dependent diabetes, Diabetes care, 5, 497-500, 1982.
(22) Feinglos, M. N. and Lebovitz, H. E., Long term safety and efficacy of glipizide, Am. J. Med., 25 (suppl. 5B), 60-66, 1983.
(23) Kradjan, W. A., Takeuchi, K. Y., Opheim, K. E. and Wood, F. C. Pharmacokinetics and pharmacodynamics of glipizide after once-daily and divided doses, Pharmacotherapy, 15 (4), 465-471, 1995.
(24) Berelowitz, M., Fischette, C., Cefalu, W., Schade, D. S., Sutfin, T., and Kourides, I. A., Comparative efficacy of once daily controlled-release formulation of glipizide and immediate-release glipizide in patients with NIDDM, Diabetes Care, 17 (12), 1460-1464, 1994.
(25) Riddle, M. C., Mcdaniel, P. A. and Tive, L. A., Glipizide-GITS does not increase the hypoglycemic effect of mild exercise during fasting in NIDDM, Diabetes Care, 20 (6), 992-994, 1997.
(26) Blonde, L., Guthrie, R. D., Tive, L., Fischette, C. The Glipizide GITS efficacy and safety trial study group. Glipizide GITS is effective and safe in a wide range of NIDDM patients: results of a double blind, placebo controlled efficacy and safety trial, Diabetes 45 (suppl. 2): 285A, 1996.
(27) British Pharmacopoeia, London The Stationery Office, Volume II, pp1862, 1999,.
(28) United States Pharmacopeia XXIII National Formulary,18, United States Pharmacopeial Convention Inc. Rockville, pp707-708, 1995.
(29) Lachman, Leon, Liberman, H. A. and Kanig, J. L., The theory and Practice of Industrial Pharmacy, Varghese Publishing House, Bombay,1991.
(30) Guidance for Industry: Dissolution testing of immediate released dosage forms. FDA, August 1997.
(31) Amidon, G. L., Lennernas, H., Shah, V. P. and Crison, J. R. A., Theoretical basis for a biopharmaceutic drug classification: the correlation of In vitro drug product dissolution and in vivobioavailability, Pharm. Res., 12, 413-420, 1995.
(32) United States Pharmacopeial Convention, Inc., July 1998, In vitro-In vivo Correlation for extended release oral dosage forms, Pharmacopeial Forum Stimuli Article, 4160-4161.
(33) Guidance for Industry, Glipizide, In vivobioequivalence and In vitro dissolution testing, Division of Bioequivalence, Office of Generic drugs, 7500 standish Place, Metro Park North, Rockville, Md. 20855.
(34) United States Pharmacopeia XXIII National Formulary,18, United States Pharmacopeial Convention Inc. Rockville, Supplement I pp2465, 1995.
(35) Shenfield, G. M., Boutagy, J. S. and Webb, C. A screening test for detecting sulfonylureas in plasma, Therapeutic Drug Monitoring, 1990, 12, 393-397.
(36) Guidance for Industry: SUPAC-MR: modified release solid oral dosage forms scale-up and postapproval changes: chemistry, manufacturing, and controls; In vitro dissolution testing and In vivobioequivalence documentation.FDA, September 1997.
(37) Shah, V. P., Tsong, Y., Sathe, P. and Liu, J. P., In vitro dissolution profile comparison-statistics and analysis of the similarity factor, f2, Pharm. Res. 15, 889-896, 1998.
(38) Tang, Y. and Gan, K., Statistical evaluation of In vitro dissolution of different brands of ciprofloxacin hydrochloride tablets and capsules, Drug. Dev. Ind. Pharm., 24(6), 549-552, 1998.
(39) Guidance for Industry: Bioavailability and bioequivalence studies for orally administered drug productsxe2x80x94General considerations.
(40) Hunt, G., Kearney, P. and Kellaway, I. W., Mucoadhesive polymers in drug delivery systems, in Drug Delivery Systems (Eds P. Johnson and J. G. Lloyd-Jones), Ellis Horwood Ltd. Chichester, UK, and VHC Verlagsgesellschaft GmbH Weinheim, Germany, pp.180-199, 1987.
(41) Sau-Hung, Leugand, S. and Robinson, J. R., Bioadhesives in drug delivery, Polym. News 15, 333, 1990.
(42) Chen,m J. L. and Cyr, G. N., Composition producing adhesion through hydration, in Adhesion in Biological systems (Ed. R. S. Manly), Academic Press, new York and London, ch. 10, pp. 163-167, 1970,
(43) P. Bottenberg et al., Development and testing of bioadhesive fluoride containing slow release tablets for oral use, J. Pharm. Pharmacol., 43,457-464, 1991.
(44) Polyox Water soluble resins, NF in sustainedxe2x80x94Release Oral pharmaceutical applications, Union Carbide, Danbury Conn., Literature#UC377.
(45) Gupta, A., Garg, S. and Khar, A. K., Measurement of bioadhesive strength of mucoadhesive buccal tablets: Design of an In vitro assembly, Indian Drugs, 30, 152-155, 1993.
(46) Martin, F., Physical Pharmacy, Fourth Edition, Lea and Febiger, Philadelphia, London, 305-330.
(47) Ritger, P. L. and Peppas, N. A., 1987b, A simple equation for description of solute release II. Fickian and anamolous release from swellable devices. Journal of Controlled Release, 5, 37-42.
The following U.S. Pat. Nos. are incorporated herein by reference:
4,346,709 August, 1982 Schmitt 128/260
4,696,815 September, 1987 Schepky et al. 424/80
4,803,076 February, 1989 Ranade 424/438
5,024,843 June, 1991 Kuczynski et al. 424/499
5,091,190 February, 1992 Kuczynski et al
5,100,669 March, 1992 Hyon et al. 424/426
5,512,297 April, 1996 Baichwal 424/451
6,245,357 June, 2001, Edgren, et. al
1. Field of the Invention
The present invention relates to a composition useful for reducing serum glucose levels by an oral controlled release system. Also, the invention describes a method of reducing serum glucose levels by an oral controlled release dosage form incorporating glipizide and the dosage form administered once a day will provide therapeutic levels of the drug throughout the day.
2. Background of the Invention
Diabetes mellitus (DM) is a complex chronic disorder of carbohydrate, fat, and protein metabolism that results primarily either from a partial or complete lack of insulin secretion by the beta cells of the pancreas or from defects in cellular insulin receptors.
The two primary types of Diabetes Mellitus can be described based on the level of insulin production by the person""s pancreatic beta cells:
Type I Diabetes (IDDM)xe2x80x94Little or no insulin is produced as the pancreatic beta cells have been destroyed by the body""s own immune system. Type I Diabetes is also known as Insulin Dependent Diabetes Mellitus (IDDM) since the individual is dependent on daily insulin injections for his survival. Between 5-10% of all diabetics are IDDM (Ref.:1; xe2x80x94American Diabetes Association. Diabetes 1996 Vital Statistics. Rockville, Md.: American Diabetes Association, 1996.)
Type II Diabetes (NIDDM)xe2x80x94Pancreatic beta cells produce insulin but not in sufficient quantities to maintain healthy blood glucose levels. Non-Insulin Dependent Diabetes Mellitus (NIDDM) results from the deterioration in the molecular machinery that mediates the effectiveness of insulin function on cells (e.g. insulin resistance and inadequate insulin secretion). Between 90-95% of all diabetics are NIDDM (Ref.: 2xe2x80x94Harris, M. I., Cowie, C. C., Stern, M. P. eds. Diabetes in America, 2nd. ed. National Institutes of Health. National Institute of Diabetes and Digestive and Kidney Diseases. NIH Publication No. 95-1468, 1995).
The pathological complications of diabetes are fundamentally related to hyperglycemia. For example, it appears that hyperglycemia can induce increased aldose reductase activity which affects sorbitol accumulation, depletes neural myoinositol, and alters Naxe2x80x94K ATPase activity. Hyperglycemia also increases diacylglycerol and xcex22 protein kinase C activity, which in turn alters the contractility and hormone responsiveness of vascular smooth muscle, and alters endothelial cell permeability. Moreover, hyperglycemia is associated with accelerated non-enzymatic glycosylation processes which activate endothelial and macrophage receptors for advanced glycosylation endproducts (AGEs), and alters lipoproteins as well as matrix and basement membrane proteins. It is clear that the consequences of glucose toxicity are globally distributed throughout the physiology of the diabetic patient.
If the diabetes is poorly controlled it can lead to diabetic complications. Diabetic complications are much more common in type 2 patients with approximately 50% suffering from one or more complications at the time of diagnosis (Ref.:3xe2x80x94Clark, C. M., Vinicor, F. Introduction: Risks and benefits of intensive management in non-insulin-dependent diabetes mellitus. The Fifth Regensrief Conference. Ann Intern Med, 124(1, pt 2), 81-85, 1996.).
Diabetic complications can be split into two main categories:
Microvascular
Macrovascular
Diabetes affects the small blood vessels throughout the body. Damage to these vessels and the basement membrane causes impaired delivery of nutrients and hormones to the tissues, resulting in tissue damage. The sites most affected are the retina, renal glomerulus and the nerve sheath.
Retinopathy
This is a major cause of blindness in diabetic patients. Microangiopathy affecting the retina develops over a number of years. Vision is not affected by all retinopathies, however prompt treatment is necessary in controlling the condition and maintaining vision.
Nephropathy
This is a major cause of mortality in diabetics. Diabetic nephropathy is recognized by the detection of albuminuria from urine tests. Progress is evaluated by measuring albumin excretion (microalbuminuria=30-300 mg/24 hr; macroalbuminuria greater than 300 mg/24 hr) from a timed urine collection.
Neuropathy
Diabetic neuropathy affects the sensory nerve system causing pain (sharp, stabbing or burning particularly on the shins and soles of feet). Other symptoms of autonomic neuropathy include impotence in men, gastrointestinal dysfunction and lack of sweating in the feet.
Macrovascular Complications
This affects the larger vessels in the body and is more likely in type 2 diabetes patients. The complications of high blood glucose levels both in the short and long term are what make diabetes a frightening disease (Ref.: 4xe2x80x94Porte, J. and Schwartz, M. W., Diabetes complications: Why is glucose potentially toxic?, Science, 272, 699-700, 1996). The most common acute symptoms (thirst, frequent urination, fatigue and weight loss) can be explained by how the body attempts to deal with the high levels of sugar in the blood system. When sugar levels are high blood begins to thicken. This signals the body to consume fluids (thirst). The kidneys monitor fluid levels and removes the excess fluids through urination (frequent urination). When sugar levels are elevated, sugars spill into the urine and energy and calories are lost (fatigue and weight loss). Numerous years of high or uncontrolled BGL produce severe long term complications. Diabetes is a result of a fundamental problemxe2x80x94the body is unable to process sugar into energy correctly. Over time this fundamental problem affects many areas of a person""s body making diabetes xe2x80x9cThe Department Store of Diseasexe2x80x9d. Long term problems of diabetes include:
Long-Term Complications of Diabetes
Injuries in large blood vessels endanger the heart, particularly in people with existing heart disease or high blood pressure.
Cardiovascular Complications
Heart attacks account for 60% and strokes for 25% of deaths in all diabetics. A recent study reported that people with type 2 diabetes and no history of a heart disease have the same seven-year risk for a heart attack as nondiabetics with heart disease. Both type 1 and 2 diabetes accelerate the progression of atherosclerosis, a process whereby layers of yellowish plaque made up of cholesterol, fats, and other particles build up in the walls of arteries. As the arteries narrow, blood flow slows and the blood vessels may become blocked. This can lead to coronary artery disease, heart attack, or stroke. Type 2 diabetes are more likely than the general population to have high triglyceride levels and lower high density lipoprotein (HDL)xe2x80x94both risk factors for heart disease. Insulin resistance is also often accompanied by high blood pressure, another major cause of heart attack, stroke, and heart failure (ref.:-5: Ishii, H., Jirousek, M. R., Koya, D., Takagi, C., Xia, P., Clermont, A., Bursell, S. E., Kern, T. S., Ballas, L. M., Heath, W. F., Stramm, L. E., Feener, E. P. and King, G. L., Amelioration of vascular dysfunctions in diabetic rats by an oral PKC xcex2inhibitor, Science, 272, 728-731, 1996).
Mental Function and Dementia
Studies indicate that patients with type 2 diabetes face a higher than average risk of developing dementia caused either by Alzheimer""s disease or problems in blood vessels in the brain. Problems in attention and memory can occur even in people under 55 who have had diabetes for a number of years.
Other Complications
People with diabetes are at higher risk for influenza and its complications, including pneumonia, possibly because the disorder neutralizes the effects of protective proteins on the surface of the lungs. Women with type 2 diabetes face a higher risk for uterine cancer although only if they are obese. Both women and men with diabetes appear to have a higher risk for colon and rectal cancers.
Complications in Pregnancy
Both preexisting diabetes in pregnant women and temporary diabetes that occurs during pregnancy (gestational diabetes) can increase the risk for birth defects. Because glucose crosses the placenta, a woman with diabetes can pass high levels of blood glucose to the fetus. In response, the fetus secretes large amounts of insulin. This combination of high fetal blood levels of insulin and glucose leads to excessive fetal growth. It may also contribute to delayed maturation of the lungs or to the death of the fetus.
Hypoglycemia
Intensive insulin or treatments that produce insulin, such as sulfonylureas, increase the risk of hypoglycemia (or insulin shock), which occurs if blood glucose levels fall below normal (Ref.: 6xe2x80x94UKPDS Group. UK Prospective Diabetes Study 33: Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes. Lancet, 352, 837-853, 1998). Hypoglycemia may also be caused by insufficient intake of food, exercise, or alcohol intake. Usually the condition is manageable, but occasionally, it can be severe or even life threatening, particularly if the patient fails to recognize the symptoms (refs:-7,8xe2x80x94Incidence and risk factors for serious hypoglycemia in older persons using insulin or sulfonylurea. Arch Int Med, 8, 25, 1997. Tight control for type 2 diabetes. HealthNews, 10, 25, 1998). Mild symptoms usually occur at moderately low and easily correctable levels of blood glucose; they include sweating, trembling, hunger, and rapid heartbeat. Severely low blood glucose levels can precipitate neurologic symptomsxe2x80x94confusion, weakness, disorientation, combativeness, and in rare and worst cases, coma, seizure, and death. Patients who experience repeated episodes of hypoglycemia may become insensitive to symptoms; even a single recent episode of hypoglycemia may make it more difficult to detect the next episode. By rigorously avoiding low blood glucose, such patients can regain the ability to sense the symptoms. Experts have been concerned that the increased incidence of hypoglycemia accompanying strict blood glucose control could cause mental deterioration over time. This observation is attributed to the unusual and interesting feature of the brain that, while like other organs systems in its reliance on blood glucose concentration for function, the brain differs from other organs in that it does not need insulin to utilize glucose. Boyle et al. (1995) (9) have reported that hypoglycemia is likely to lead to a reversible, maladaptive central nervous system tolerance to subnormal plasma glucose concentrations. Specifically, certain autonomic portions of the brain adapt physiologically, learning to tolerate low blood glucose levels. By contrast, the rest of the brain, and in particular the cognitive portions, do not possess this capacity. Defective glucose counterregulation can occur even after only a single episode of hypoglycemia. Patients who experience repeated episodes of hypoglycemia often lose their capacity to recognize the symptoms typically associated with hypoglycemia or impending insulin shock, a condition called xe2x80x9chypoglycemia unawareness.xe2x80x9d Because the patient doesn""t appreciate his or her own status, blood glucose levels can then fall so low that serious neurological problems ensue, including coma and seizure.
The Diabetes Control and Complications Trial (DCCT)(10), a ten-year study completed in mid-1993, demonstrated that tight or xe2x80x9cintensivexe2x80x9d control of blood glucose levelsxe2x80x94i.e., frequent self-monitoring of glucose levels and maintenance of these levels as close as possible to those in nondiabetics-significantly reduces diabetes-associated complications, such as retinopathy, nephropathy and neuropathy. The DCCT (11) showed that the frequency of health complications was 40-75% lower for persons in the intensive control group than for those in the conventional treatment group. It has since become a central doctrine of diabetic management that the intensive control of hyperglycemia is critical to effective retardation or delay in the appearance or progression of the late complications of the disease. However, it was found in the DCCT that patients in the intensive treatment group more often suffered from seizures or coma or required another person""s assistance to recover from hypoglycemia than did patients treated less intensively. The chief adverse complication associated with intensive therapy was 3-fold increase in the incidence of severe hypoglycemia, defined as the need for assistance from others, as compared to diabetics undertaking conventional therapy. Thus, the danger in maintaining artificially a patient""s blood glucose within the narrow, normal range-the essence of intensive control prescribed according to the DCCTxe2x80x94is that such regimens can induce recurrent low blood-glucose levels, raising the threat of seizure or a coma with little or no warning. Lewin in 1996(12) has recognized that tight control of the blood glucose levels poses a difficult dilemma. Specifically, while tight control of blood glucose levels appears to be required to control hyperglycemia-associated pathology, in practice the patient often overcorrects, thereby inducing repeated episodes of hypoglycemia, giving rise to hypoglycemia unawareness. In order to provide a long term solution to Type II sufferers, a comprehensive treatment must be provided to assist them in maintaining healthy or near normal blood sugar levels. Boyle et al. have also found that, because the body, and especially the brain, adapts to lower blood sugar levels, there is little margin between the blood glucose level at which hypoglycemic signs become perceptible and the level at which dangerous cognitive impairment occurs. Accordingly, patients who use rigorous treatment regimens to maintain near-normal plasma glucose levels are at increased risk for seizures and comas. It is difficult to achieve the tightest level of glycemic control (to minimize microvascular and other complications) while at the same time avoiding even a slight degree of hypoglycemia (to avoid central nervous system tolerance to subnormal glucose levels). Thus, there is a clear need for additional understanding of these interrelated physiological processes, as well as for new diabetes treatment regimens that avoid the problems that have so far plagued effective patient management.
Drug 
Glipizide(1-cyclohexyl-3-[[p-[2-(5-methylpyrazinecarboxamido)ethyl]phenyl]sulfonyl] urea), a second generation sulfonylurea is effective in controlling the blood glucose in patients with NIDDM (13-16).
Glipizide is a whitish odorless powder with a pKa 5.0 and is insoluble in water and alcohols but soluble in 0.1N NaOH (17,18). DOSE : There is no fixed dosage regimen for the management of diabetes mellitus with glipizide or any other hypoglycemic agent. In addition to the usual monitoring of urinary glucose, the patient""s blood glucose must also be monitored periodically to determine the minimum effective dose for the patient; to detect primary failure, i.e., inadequate lowering of blood glucose at the maximum recommended dose of medication; and to detect secondary failure, i.e., loss of an adequate blood-glucose-lowering response after an initial period of effectiveness. Glycosylated hemoglobin levels may also be of value in monitoring the patient""s response to therapy.
Short-term administration of glipizide may be sufficient during periods of transient loss of control in patients usually controlled well on diet. As with other sulfonylurea-class hypoglycemics, many stable non-insulin-dependent diabetic patients receiving insulin may be safely placed on glipizide. Dosage may be adjusted at intervals of several days by amounts of 2.5 to 5 mg daily to a maximum of 40 mg daily.
Pharmacokinetics
Glipizide is completely absorbed and peak plasma conc. varying between 380 to 611 ng/ml (0.85 to 1.35 mmol/ml) are attained usually 1-3 hr after a single oral 5 mg dose. Plasma concentrations decline to 12.0 ng/ml after 24 hr. The apparent volume of distribution of glipizide in man has been reported to be 11.5 to 25 liters and that of central compartment 6 to 10 liters. It is extensively bound to human serum proteins. Glipizide is almost completely metabolized and the metabolites are devoid of hypoglycaemic activity. The principal metabolites of the glipizide are the 4-trans-hydroxycylcohexyl derivative, the 3-cis-hydroxycyclohexyl derivative, and N-(2-acetylamino-ethyl phenyl-sulphonyl)-Nxe2x80x2 cyclohexyl urea (19).
Half life : It has a half life of approximately 2-4 hr.
Mechanism Of Action of Controlled Release Tablets
Glipizide appears to lower blood glucose acutely by
(i) Insulin release from pancreatic xcex2 cells: This effect is dependent upon functioning beta cells in the pancreatic islets. It binds to ATP-sensitive potassium channel on the beta cell membrane. Binding of this sulfonylurea inhibits the efflux of potassium ion through the channel and results in depolarization which in turn opens a calcium channel and results in calcium influx and release of preformed insulin.
(ii) Reduction of serum glucagon concentration: Chronic administration of sulfonylurea to NIDDM patients reduces serum glucagon levels which contributes to the hypoglycemic effects of the drug.
(iii) Potentiation of insulin action on the target tissues: Increased binding of insulin to tissue receptor occurs during in vivo sulfonylurea administration.
Effects on Blood Glucose
The effectiveness of glipizide extended-release tablets in NIDDM at doses from 5-60 mg once daily has been evaluated in 4 therapeutic clinical trials each with long-term open extensions involving a total 598 patients. Once daily administration of 5, 10, and 20 mg produced statistically significant reductions from placebo in hemoglobin A1c, fasting plasma glucose and postprandial glucose in mild to severe NIDDM patients. In a pooled analysis of the patients treated with 5 mg and 20 mg, the relationship between dose and glipizide extended-release""s effect of reducing hemoglobin A1c was not established. However, in the case of fasting plasma glucose patients treated with 20 mg had a statistically significant reduction of fasting plasma glucose compared to the 5 mg-treated group.
The reductions in hemoglobin A1c and fasting plasma glucose were similar in younger and older patients. Efficacy of glipizide extended-release was not affected by gender, race, or weight (as assessed by body mass index). In long term extension trials, efficacy of glipizide extended-release was maintained in 81% of patients for up to 12 months.
In an open, two-way crossover study 132 patients were randomly assigned to either glipizide extended-release or glipizide for 8 weeks and then crossed over to the other drug for an additional 8 weeks. Glipizide extended-release administration resulted in significantly lower fasting plasma glucose levels and equivalent hemoglobin A1c levels, as compared to glipizide (20).
Pharmacokinetics and Metabolism
Glipizide is rapidly and completely absorbed following oral administration in an immediate release dosage form. The absolute bioavailability of glipizide was 100% after single doses in patients with NIDDM. Beginning 2 to 3 hours after administration of glipizide extended-release tablets, plasma drug concentrations gradually rise reaching maximum concentrations within 6 to 12 hours after dosing. With subsequent once daily dosing of glipizide extended-release tablets, effective plasma glipizide concentrations are maintained throughout the 24 hour dosing interval with less peak to through fluctuation than that observed with twice daily dosing of immediate release glipizide. The mean relative bioavailability of glipizide in 21 males with NIDDM after administration of 20 mg glipizide extended-release tablets, compared to immediate release glipizide (10 mg given twice daily), was 90% at steady state. Steady state plasma concentrations were achieved by at least the fifth day of dosing with glipizide extended-release tablets in 21 male with NIDDM and patients younger than 65 years. Approximately 1 to 2 days longer were required to reach steady state in 24 elderly ( greater than 65 years) males and females with NIDDM. No accumulation of drug was observed in patients with NIDDM during chronic dosing with glipizide extended-release tablets. Administration of glipizide extended-release with food has no effect on the 2 to 3 hour lag time in drug absorption. In a single dose, food effect study in 21 healthy males subjects, the administration of glipizide extended-release immediately before a high fat breakfast resulted in a 40% increase in the glipizide mean Cmax value, which was significant, but the effect on the AUC was not significant. There was no change in glucose response between the fed and fasting state. Markedly reduced GI retention times of the glipizide extended-release tablets over prolonged periods (e.g., short bowel syndrome) may influence the pharmacokinetic profile of the drug and potentially result in lower plasma concentrations. In a multiple dose study in 26 males with NIDDM, the pharmacokinetics of glipizide were linear over the dose range of 5 to 60 mg of glipizide extended-release in that the plasma drug concentrations increased proportionately with dose. In a single dose study in 24 healthy subjects, four 5 mg, two 10 mg, and one 20 mg glipizide extended-release tablets were bioequivalent(20).
In patients with NIDDM, the drug has a much greater effect in potentiating meal induced insulin secretion (21,22). Glipizide is an exception among all sulfonylureas, whose ability to potentiate nutrient stimulated insulin secretion persists during long term therapy while with other drugs, this effect is lost after 6-12 months of therapy. It has been shown that glipizide-GITS (an extended release tablet for oral use) is more effective than immediate release glipizide in reducing fasting plasma glucose levels (23). Both formulations reduce postprandial plasma glucose levels equally, however glipizide-GITS exerts its control in the presence of lower plasma glipizide concentrations in addition to significantly lower insulin and c-peptide levels. This suggests that glipizide-GITS improves insulin sensitivity. Studies have proved that chronic use of extended-release glipizide does not enhance the hypoglycemic effect of fasting plus mild exercise for people with NIDDM (24-26). It is clear that the controlled release preparations of glipizide have shown better efficacy than immediate release dosage.
Contraindications
Immediate and Extended Release Tablets
Glipizide is Contraindicated in Patients with
Known Hypersensitivity to the Drug
Diabetic ketoacidosis, with or without coma. This condition should be treated with insulin.
Drug Interactions
The hypoglycemic action of sulfonylureas may be potentiated by certain drugs including nonsteroidal anti-inflammatory agents and other drugs that are highly protein bound, salicylates, sulfonamides, chloramphenicol, probenecid, coumarins, monoamine oxidase inhibitors, and beta adrenergic blocking agents. When such drugs are administered to a patient receiving glipizide, the patient should be observed closely for hypoglycemia. When such drugs are withdrawn from a patient receiving glipizide, the patient should be observed closely for loss of control. In vitro binding studies with human serum proteins indicate that glipizide binds differently than tolbutamide and does not interact with salicylate or dicumarol. However, caution must be exercised in extrapolating these findings to the clinical situation and in the use of glipizide with these drugs.
Certain drugs tend to produce hyperglycemia and may lead to loss of control. These drugs include the thiazides and other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blocking drugs, and isoniazid. When such drugs are administered to a patient receiving glipizide, the patient should be closely observed for loss of control. When such drugs are withdrawn from a patient receiving glipizide, the patient should be observed closely for hypoglycemia.
A potential interaction between oral miconazole and oral hypoglycemic agents leading to severe hypoglycemia has been reported. Whether this interaction also occurs with the intravenous, topical, or vaginal preparations of miconazole is not known.
The effect of concomitant administration of fluconazole and glipizide has been demonstrated in a placebo-controlled crossover study in normal volunteers. All subjects received glipizide alone and following treatment with 100 mg of fluconazole as a single daily oral dose for 7 days. The mean percentage increase in the glipizide AUC after fluconazole administration was 56.9% (range: 35 to 81).
Adverse Effects
Gastrointestinal
Gastrointestinal disturbances are the most common reactions. Gastrointestinal complaints were reported with the following approximate incidence: nausea and diarrhea, one in seventy; constipation and gastralgia, one in one hundred. They appear to be dose-related and may disappear on division or reduction of dosage. Cholestatic jaundice may occur rarely with sulfonylureas, glipizide should be discontinued if this occurs.
Dermatologic
Allergic skin reactions including erythema, morbilliform or maculopapular eruptions, urticaria, pruritus, and eczema have been reported in about one in seventy patients. These may be transient and may disappear despite continued use of glipizide; if skin reactions persist, the drug should be discontinued. Porphyria cutanea tarda and photosensitivity reactions have been reported with sulfonylureas.
Miscellaneous
Dizziness, drowsiness, and headache have each been reported in about one in fifty patients treated with glipizide. They are usually transient and seldom require discontinuance of therapy.
Disadvantages of the Known Formulations
Glipizide does not accumulate in the plasma following repeated oral dosing. Glipizide tablets are available, e.g., in 5 and 10 mg immediate release formulations and extended release dosage forms Glucotrol XL 5 mg, 10 mg and 20 mg (Pfizer Inc. USA) and Glytop SR 5 mg (Sidmak Laboratories (India) Ltd)
Immediate release tablets formulated with a sulfonylurea based on an acidified and/or alkalized excipient and an inert polar solvent, such as polyethylene glycol, are described by U.S. Pat. No. 4,696,815. These pH regulated, immediate release formulations are described as improving the dissolution of acidic, amphoteric or basic antidiabetic sulfonylurea compounds, respectively. For example, the alkalized excipient is said to promote improved dissolution of glipizide, which is an acid compound. An analogous immediate release formulation with an acidified and/or alkalized excipient, an inert polar solvent and polyvinylpyrrolidone is also described by U.S. Pat. No. 4,696,815.
Erodible poly(orthoester) or poly(orthocarbonate) devices for implantation or insertion into a patient are described by U.S. Pat. No. 4,346,709, for delivering a drug in a controlled manner, including oral hypoglycemic drugs such as the sulfonylurea hypoglycemics, acetohexamide, glypinamide, chlorpropamide, tolazamide, tolbutamide, phenformin.
A controlled release delivery system using melt spun biodegradable polymers as a carrier or host material for a bio-effecting agent such as a pharmaceutical active or a hormonal compound, including glipizide, for e.g., oral administration, is described by U.S. Pat. No. 5,518,730.
Controlled release microspheres for administration by, e.g., the oral route and comprising polylactic acid and a water soluble physiologically active substance and having a mean particle size of from about 0.01 xcexcm to 300 xcexcm are described by U.S. Pat. No. 5,100,669 as including active substances such as the antidiabetic agents glipizide, glymidine sodium, phenformin hydrochloride, methformin, buformin hydrochloride.
Uniformity and predictability of therapeutic levels of sulfonylureas and resulting blood sugar levels are considered to be desirable in the management of diabetic patients, and in particular, for the management of type II diabetic patients. For example, in tests with art-known extended release glipizide (formulations based on orally ingestible osmotic devices, as discussed herein below) it has been shown that fasting plasma glucose levels were significantly lower in patients treated with controlled release glipizide than with immediate-release glipizide.
Extended release sulfonylurea formulations with improved dissolution properties, and particularly, extended release formulations of second generation sulfonylureas, are therefore a desirable addition to the medical treatment of diabetes, including type II diabetes. Of these second generation drugs, efforts to provide controlled release have focused on glipizide. Art-known extended release glipizide formulations are available as osmotic based dosage forms, such as, for example, Glucotrol XL Extended Release TabletRTM (Pratt Pharmaceuticals; 5 to 60 mg unit doses). As with other art-known extended release glipizide, discussed hereinbelow, Glucotrol XLRTM is prepared as an osmotic pump formulation. Specifically, Glucotrol XL.RTM is prepared as an osmotically active drug core surrounded by a semipermeable membrane. The core itself is divided into two layers: an xe2x80x9cactivexe2x80x9d layer containing the drug, and a xe2x80x9cpushxe2x80x9d layer containing pharmacologically inert (but osmotically active) components. The membrane surrounding the tablet is permeable to water but not to drug or osmotic excipients. As water from the gastrointestinal tract enters the osmotically active material, the tablet pressure increases in the osmotic layer and xe2x80x9cpushesxe2x80x9d against the drug layer, resulting in the release of drug through a small laser-drilled orifice in the membrane on the drug side of the tablet.
Other osmotic pump devices and formulations for administering glipizide are described in U.S. Pat. Nos. 5,091,190 and 5,024,843 (Kucrynski et al.) and in U.S. Pat. No. 4,803,076 (Gautman). These patents describe the delivery of glipizide in a controlled manner by the use of an oral formulation based on another osmotic pump design. U.S. Pat. No. 4,792,448 (Gautman) has also described the zero order release of glipizide using a device described as a strip covered by an impermeable wall with uncovered areas.
U.S. Pat. No. 6,245,3576 teaches a controlled release dosage form comprising an osmotic core, an interior wall, said interior wall comprises a hydrophobic substance and a hydrophilic substance and a fluid permeable exterior wall surrounding the interior wall. However, this system is restricted to analgesic compositions only. In addition, this combination is for delivering higher quantities of drugs and not suitable for releasing lower quantities of drugs, which are required in certain kinds of physiological conditions such as diabetes II. In case of diabetes II, the drug release should not be more than 40% of the drug at a time. In case, if the drug is released more, then it triggers sudden lowering of serum glucose level, which in turn cause adverse effects and complications to the patient. Therefore, there is a need to construct a slow and controlled release drug delivery system. The present invention meets the above requirement by providing a oral controlled release system for diabetes II.
All of these formulations, therefore, are prepared from a plurality of osmotic pump devices that require complex manufacturing processes with attendant high costs. Moreover in osmotic pumps, the amount of drug added is more than the dose of the drug in order to achieve a constant release. This may lead to increase in cost in case of costly drugs.
Therefore, there has not previously been a fully satisfactory and economical formulation for providing a predictable and uniform treatment regimen, which avoids the need for the construction of complex devices for oral administration and that have the further advantage of simplifying treatment and improving patient compliance while both enhancing the bioavailability of the antidiabetic drug and prolonging the release of the drug. A significant problem facing the pharmaceutical formulator attempting to prepare a bioavailable oral sustained release dosage form of a sulfonylurea relates to the ability of the dosage form to release the drug over the desired period of time to such an extent that the sulfonylurea content of the dosage form will be effectively bioavailable. One aspect of this problem is the fact that sulfonylureas are relatively insoluble and therefore inherently difficult to be solubilized from an oral dosage form in the gastrointestinal tract and then be absorbed through the walls of the gastrointestinal tract. This solubility and bioavailability problem has been overcome with respect to immediate release oral sulfonylurea dosage form by utilizing a solubilizing agent, as discussed above. However, such agents are expected to cause the fast, i.e., immediate, release of all of the sulfonylurea when orally administered. Therefore, the use of such solubilizing agents would not necessarily be considered desirable in sustained release oral dosage forms, where the goal is to slow the release of drug from the dosage form over an extended period of time. Thus, there is a continuing need in the art for a relatively simple and economical controlled release sulfonylurea formulation for oral administration that is fully bioavailable and suitable for administration once every 24 hours.
The present invention provides a composition useful for reducing serum glucose levels by an oral controlled release system
The present invention is directed to an improved and more economical method for the stable and convenient treatment of diabetes of the type II that is responsive to control by a sulfonylurea antidiabetic agent. Also the present invention is directed to a method for preparing a bioavailable controlled release 24 hour formulation for antidiabetic drugs such as sulfonylurea, glipizide drugs.
Accordingly, the present invention relates to a composition useful for reducing serum glucose levels by an oral controlled release system and a method for treating diabetes in a human being by controlling the blood glucose level (BGL) and reducing the complications associated with diabetic hyperglycemia and also the long term management of Non-Insulin Dependent Diabetes Mellitus (NIDDM) by avoiding the problems associated with the tight control of BGL, i.e., hypoglycemia tolerance and seizures. The invention is directed to a novel, solid, hydrophilic matrix controlled release oral dosage form where the dosage form contains a therapeutically effective amount of antidiabetic drug in the matrix ensuring complete bioavailability of the drug from the matrix of the tablet and the formulation undergoes substantially or approaches zero order release of active drug and the concentration of the excepients and the water swellable polymers is chosen in such a way that the erosion or dissolution rate of the polymer is equal to the swelling rate of the polymer to get a constant release. Also, the concentration is chosen in such a way that the tablet will be fully dissolved at the same time the last of the drug is released and in addition a bioadhesive polymer may also be added to increase the residence time of the dosage form in the g.i.t. and at high concentration of the polymer, beta cyclodextrin may also be added to improve the release kinetics.
An object of this invention is to provide a dosage form for delivering glipizide in a rate controlled amount, and which dosage form substantially overcomes the hypoglycemia associated with the tight control of blood glucose levels.
One of the main objects of the invention is to provide a composition for reducing glucose serum levels by oral controlled release system.
Another object of the invention is to provide a regimen to achieve near normal blood glucose levels in the patient, with a low incidence of undesirable side effects for the therapy.
Still another object of the present invention is to reduce the risk of long term damage to organs and tissues resulting from sustained hyperglycemia.
Still another object of the present invention is to enable the patient to maintain as near normal a lifestyle as possible while ensuring adequate control of his or her diabetes.
Yet another object of the present invention is to provide a dosage form for orally administering glipizide in a rate-controlled dose for blood-glucose lowering therapy.
Yet another object of the invention is to provide a method for treating hyperglycemia by orally administering glipizide in a rate-controlled dose per unit time to a human being in need of hyperglycemia therapy.
One more objects of the invention is to provide a pharmaceutical dosage form that makes available controlled and sustained glipizide therapeutic activity to a patient in need of glipizide therapy.
Another object of the invention is to provide a novel dosage form manufactured as hydrophilic, swellable and erodible device that can administer glipizide to a biological receptor site to produce the desired glipizide pharmacological effects.
Another object of the present invention is to provide a dosage form that can deliver the substantially aqueous insoluble drug glipizide at a controlled and beneficial known rate over time.
Another object of the present invention is to provide a complete pharmaceutical glipizide regimen comprising a composition comprising glipizide that can be dispensed from a drug delivery dosage form, the use of which requires intervention only for initiation and possibly for termination of the regimen.
It is also an object of the invention to provide oral anti-diabetic glipizide pharmaceutical compositions.
It is a further object of the invention to provide a process for preparing said glipizide compositions.
Another object of the invention is to provide a dosage form comprising the drug N-[2-[4-[[[(cyclohexylamino)carbonyl]-amino]sulfonyl]phenyl]ethyl]-5-methyl pyrazinecarboxamide and a pharmaceutically acceptable carrier that forms and provides a dispensable composition when the dosage form is delivering the drug to the patient.
It is also an object of the invention to provide a novel and economical controlled release dosage formulation of glipizide.
Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.